ABSTRACT Of the many stressors associated with a breast cancer diagnosis, job loss is one of the most impactful yet understudied. Long-term financial consequences can include difficulty paying bills, accumulation of debt, and bankruptcy. Importantly, bankruptcy in cancer survivors has been linked to decreased treatment adherence and increased mortality. Women with access to work accommodations, such as schedule flexibility, are more likely to work during chemotherapy and to retain their jobs in the long term. Similarly, women with adequate sick leave may choose to take time off while maintaining job security. However, low-income minorities are less likely to have such accommodations, leading to higher rates of job loss and financial distress. For these patients, finding a way to continue to work during treatment is critical. In the Breast Cancer and the Workforce study, which focuses on immigrant and minority women, symptom burden and lack of work accommodations were both linked to job loss. Only 57% of pre-diagnosis employed low-income women retained their jobs after treatment completion, compared to 93% of higher-income women. Of those not working, 84% attributed their lack of employment to cancer symptoms or treatment. Low-income women were less than half as likely as higher-income women to have accommodating employers and only one-fourth as likely to retain their jobs. However, patients whose confidence in asking for work accommodations improved over time were more than five times as likely to retain their jobs than those whose confidence did not improve. There is a compelling need for an effective intervention to support working during treatment in low-income immigrant and minority breast cancer patients in order to improve long-term job retention and financial stability. The goal of the proposed study is to evaluate the effectiveness of a mobile application (app) developed to promote working during adjuvant (curative) breast cancer chemotherapy. The app has a two-pronged approach: it will help women communicate with clinicians to optimize symptom control, and it will help them communicate with employers to negotiate for accommodations. Our study is grounded in evidence that communication behaviors can be taught to patients of varying English proficiency, resulting in improved responsiveness to patients' needs. Furthermore, patient-physician communication strategies can be adapted for use in the work setting. Our app applies these principles to the workplace as well as the clinic. The use of an app to deliver the intervention is appealing in light of barriers our target population faces in accessing support and the high prevalence of smartphone use. We will randomly assign English- and Spanish-speaking women who are about to undergo chemotherapy for stage I-III breast cancer to receive the app or an informational booklet (control). Participants will complete surveys at baseline and during chemotherapy to assess symptom burden and work accommodations. Surveys 4 months and 1 and 2 years post-treatment will measure long-term job retention.